This invention relates to the compacting of 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin without use of binders, and to the novel compacted forms so produced, which, by virtue of their characteristics and physical properties, are superlative biocidal water-treating agents.
As used herein the terms xe2x80x9chalogenxe2x80x9d, xe2x80x9chalogenatedxe2x80x9d, and xe2x80x9chaloxe2x80x9d are with reference to bromine or chlorine, or both.
1,3-Dihalo-5,5-dialkylhydantoins, especially 1,3-dibromo-5,5-dimethylhydantoin, 1,3-dichloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin, and 1-chloro-3-bromo-5,5-dimethylhydantoin, or mixtures of two or more of them, are biocidal agents for use in water treatment. These compounds are, in general, sparingly soluble in water. Thus typically they are supplied in solid forms such as granules, tablets, or briquettes, and delivered into the water being treated by means of water flow through an erosion feeder.
Over the years considerable effort has been devoted to the search for improved methods for producing such compounds. In U.S. Pat. No. 2,971,960 N-brominated compounds such as N-brominated 5,5-di-lower-alkyl hydantoins are formed by treating the alkylhydantoin with bromine in an acidic aqueous solution containing hypochlorite, preferably at a pH between 1 and 4. However, the method of choice has been halogenation of the alkylhydantoin in a basic aqueous medium. Almost invariably the halogen has been introduced into, or formed in situ in, the aqueous medium containing the alkylhydantoin. See in this connection U.S. Pat. Nos. 2,398,598; 2,779,764; 2,868,787; 2,920,997; 2,971,959; 3,121,715; 3,147,259; 4,532,330; 4,560,766; 4,654,424; 4,677,130; 4,745,189; PCT Publication No. WO 97/43264, published 20 November 1997; Orazi and Meseri, Anales Assoc. Quim. Argentina, 1949, 37, 192-196; Orazi and Meseri, Anales Assoc. Quim. Argentina, 1950, 38, 5-11; Corral and Orazi, J. Org. Chem., 1963, 23, 1100-1104; Jolles, Bromine and its Compounds, Ernest Benn, London, 1966, p. 365; and Markish and Arrad, Ind. Eng. Chem. Res., 1995, 34, 2125-2127.
The N,Nxe2x80x2-dihalogenated dialkylhydantoin products formed by such processes are formed as powdery solids. For use in many applications the dry powders need to be converted into larger forms such as granules, tablets, or briquettes. This in turn has presented problems associated with providing densified or compacted products with sufficient strength to withstand the physical stresses encountered in packaging, conveying, handling, shipping, storage, and use. The nature of these problems have been described, for example, in U.S. Pat Nos. 4,532,330; 4,560,766; 4,654,424; 4,677,130; 4,745,189; and 5,565,576. The approaches described in these patents for alleviating one or more such problems involve use of additional or other materials. Thus in U.S. Pat. Nos. 4,532,330 and 4,621,096, halogenated dimethylhydantoins are mixed with calcium chloride and water, and the mixture is compacted by compression into the desired shape. In U.S. Pat. Nos. 4,560,766 and 4,654,424, halogenated ethylhydantoins are used instead of halogenated dimethylhydantoins and are compacted as such, or are melt blended with halogenated dimethylhydantoins. U.S. Pat. No. 4,677,130 describes forming dry blends of the halogenated dimethylhydantoin with particulate alkali metal or alkaline earth metal salt followed by compression to form a compacted product such as a tablet. PCT Publication No. WO 97/43264 describes the use of 1,3-bromochloro-5-methyl-5-propyl-hydantoin as a binder in making compacted forms of halogenated hydantoins.
U.S. Pat. No. 4,745,189 describes formation of halogenated dimethylhydantoinby halogenating the hydantoin in an aqueous mixture under alkaline conditions in the presence of a halogenated alicyclic organic compound such as dichloromethane. The Examples of the patent describe the formation of N,Nxe2x80x2-bromochloro-5,5-dimethylhydantoin products comprised of large particles.
U.S. Pat. No. 4,560,766 teaches that halogenated dimethylhydantoinper se cannot be used for making low-dust powders, granules, tablets, flakes, compacted forms, cast forms, and carrier-coated products without the aid of a binder.
It would be of great advantage to provide particulate 1,3-dihalo-5,5-dimethylhydantoins useful for making granules, tablets, flakes, compacted forms, cast forms, and carrier-coated products without the aid of a binder, and without use in the production process of any organic halogen compound such as dichloromethane.
This invention involves the discovery, inter alia, that 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin can be compacted without need of a binder of any kind.
Accordingly, this invention provides, inter alia, novel, binder-free, pressure compacted articles of 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin, and methods of producing such compacted articles from such binder-free 1,3-dihalo-5,5-dimethylhydantoins.
The 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin are 1,3-dichloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin, and 1-chloro-3-bromo-5,5-dimethylhydantoin, and mixtures thereof. For ease of reference, such compounds (excluding 1,3-dibromo-5,5-dimethylhydantoin) are sometimes referred to hereinafter as xe2x80x9chalogenated hydantoinsxe2x80x9d. Even though devoid of a binder, pressure compacted articles formed from particulate halogenated hydantoins have remarkable crush strength. In contrast, so far as is known, all previously known particulate forms of virgin 1,3-dibromo-5,5-dimethylhydantoin cannot be pressure compacted into tablets When attempts were made to form such tablets, it was found that when released from a tableting die, the compacted shape would xe2x80x9cdelaminatexe2x80x9d, meaning that the compacted agglomerate would break apart into smaller pieces.
Moreover, when compacted without a binder, granules, tablets, briquettes, or other relatively small shapes formed from the halogenated hydantoins have excellent physical properties for use in water-treatment systems. The shapes erode at slow, but essentially constant, rates when maintained in a constant flow of water. They withstand the customary physical stresses encountered in packaging, conveying, handling, shipping, storage, and use. The compacted solid forms of this invention produced directly from the 1,3-dihalo-5,5-dimethylhydantoins other than 1,3-dibromo-5,5-dimethylhydantoin have excellent crush strength even when formed without a binder.
While many ways of producing halogenated hydantoins are known, the best way of producing them involves process technology fully described in commonly-owned copending application Ser. No. 09/484,844, referred to above.
In converting the halogenated hydantoins into granules, conventional processing equipment can be used under the usual operating conditions. Typically, the finely divided halogenated hydantoin is compressed into sheet form by means of a roll compactor. This sheet in turn is broken up into small granules by a mechanical device, such as a Chilsonator(copyright) breaker (The Fitzpatrick Company, Elmhurst, Ill.). The granules are then classified by screening into the desired size range. Undersized granules are typically recycled to the roll compactor, whereas oversized granules are recycled to the breaker device.
The formation of tablets and other compressed shapes such as briquettes from the halogenated hydantoins can also utilize known processing equipment and, for the most part, known procedures. However, in conducting compaction of the virgin halogenated hydantoins particulate solids in the absence of a binder, it is important that the compaction pressure be sufficient to induce plastic deformation and interparticulate binding of the particles. At the same time, the compaction pressure should not be so great as to produce a compacted product which delaminates on expulsion from the die. Typically, suitable compaction pressures in the practice of this invention will fall within the range of about 1000 to about 30,000 psi, and preferably in the range of about 5000 to about 25,000 psi. Such compaction can be conducted using, for example, a rotary tableting press operated at conventional rotational speeds, e.g., about 20 rpm. Another method for accomplishing the compaction is by means of pressure extrusion through a die orifice, while concurrently shearing the extrudate to produce compacted shapes of the desired size. In such operations, the compaction pressures within the die should be sufficient to induce plastic deformation and interparticulate binding of the particles, but insufficient to produce a compacted product which, when extruded, undergoes an elastic recovery of a magnitude that causes delamination of the compacted extrudate.
In operations conducted on a small scale using manually filled dies, 1,3-dichloro-5,5-dimethylhydantoin and N,Nxe2x80x2-bromochloro-5,5-dimethylhydantoin having an average particle sizes of about 108 microns and about 324 microns, respectively, have been successfully compacted into tablets without resorting to use of any binder. The tablets when released from the dies were intact and exhibited no visual surface imperfections.
The halogenated hydantoins can also be directly converted without use of a binder into whole briquettes utilizing conventional briquetting rolls operated under conventional conditions. In such operations, pressures in the range of about 1000 to about 30,000 psi are typical; more preferably, the pressures are in the range of from about 5000 to about 25,000 psi. As in the case of pressure compaction of tablets, the compaction pressure should be sufficient to induce plastic deformation and interparticulate binding of the particles, but insufficient to produce a compacted product which undergoes an elastic recovery of a magnitude causing delamination of the compacted article on exiting the rolls.
The compaction operations, whether performed in a die, by extrusion through an orifice of a die, or by roll compaction is typically conducted at ambient room temperatures. However, it is possible to either cool or warm the material being subjected to compaction. This can be accomplished either by refrigerating or directly heating the product before introducing it into the compaction apparatus, or by chilling or heating the apparatus itself such as, for example, by using rolls equipped with heating or cooling coils or other means for effecting temperature regulation. The compaction operation itself can, and in many cases does, result in generation of heat within the compacted shape. Generally speaking, the compaction operations pursuant to this invention can be performed at temperatures in the range of about 5 to about 80xc2x0 C.
It will be understood and appreciated that departures from the numerical ranges given herein for pressures and temperatures are permissible in the practice of this invention, whenever such departures are deemed necessary or desirable, provided only that such departures do not materially affect in an adverse manner the processing or the properties of the product being produced.
Typically, compacted products of this invention, such as tablets, briquettes, and pucks, formed without use of a binder, will have a crush strength in the range of from about 75 to about 200 pounds per inch of thickness. Thus, it is now possible to provide binder-free compacted products having the strength needed to withstand the physical stresses encountered in packaging, conveying, handling, shipping, storage, and use.
When converted into tablets, briquettes, pucks, and other compacted shapes with use of a suitable binder, the halogenated hydantoins form compacted articles of even greater crush strength. Markedly superior binding agents for use with the halogenated hydantoins are the micronized polyolefins waxes and the micronized polyfluorocarbon waxes described in commonly-owned co-pending application Ser. No. 09/487,816, filed Jan. 18, 2000.
Granules, tablets, and briquettes produced from halogenated hydantoins are of particular utility as biocidal agents for use in swimming pools, spas, toilet bowl cleaners, cooling towers, air washer systems, wastewater, pulp and paper processing operations, oil field applications, and decorative fountains.
In the practice of this invention, the halogenated hydantoin particulate solids used in compaction without a binder are pressure-compactible halogenated hydantoin particulate solids. By this is meant that upon application of pressure to the virgin material in a die, a shape is produced that can be removed from the die without breakage occurring. Experimental evidence to date indicates that 1,3-dichloro-5,5-dimethylhydantoin having an average particle size even as small as about 100 microns or perhaps even less can be successfully pressure compacted into shape-retentive articles. In the case of N,Nxe2x80x2-bromochloro-5,5-dimethylhydantoins the available experimental evidence indicates that somewhat larger average particle size product may possibly be required in order to produce shape-retentive articles without use of a binder. The particle size distributions of the halogenated hydantoin may also contribute to the efficacy with which such iparticulate solids can be compacted. Thus in any situation where the pressure compactibility of a given supply of halogenated hydantoin has not been established, it is desirable to perform a preliminary test to determine its suitability in forming a compacted article pursuant to this invention.
Thus, in a preferred group of 1,3-dichloro-5,5-dimethylhydantoin solids in which the average particle size is in the range of about 100 to about 300 microns, 50% of the particles have a particle size of at least about 70 microns.
In a particularly preferred group of 1,3-dichloro-5,5-dimethylhydantoin solids in which the average particle size is in the range of about 100 to about 300 microns, 10 percent of the particles have a particle size of at least about 180 microns, 25 percent of the particles have a particle size of at least about 120 microns, 50 percent of the particles have a particle size of at least about 70 microns, 75 percent of the particles have a particle size of at least about 35 microns, and 90 percent of the particles have a particle size of at least about 20 microns.
In a preferred group of N,Nxe2x80x2-bromochloro-5,5-dimethylhydantoin solids in which the average particle size is in the range of about 250 to about 350 microns, 50% of the particles have a particle size of at least about 170 microns.
In a particularly preferred group of N,Nxe2x80x2-bromochloro-5,5-dimethylhydantoin solids in which the average particle size is in the range of about 250 to about 350 microns, 10 percent of the particles have a particle size of at least about 800 microns, 25 percent of the particles have a particle size of at least about 400 microns, 50 percent of TA0 the particles have a particle size of at least about 170 microns, 75 percent of the particles have a particle size of at least about 60 microns, and 90 percent of the particles have a particle size of at least about 20 microns.
As also described above, this invention provides products in which one or more of the halogenated hydantoins are converted into granules, tablets, briquettes, pucks, or any other larger sized product, however produced. Typical operations of this type have been described above. Other procedures include, for example, mixing the solid halogenated hydantoin with other dialkylhydantoins and if desired, heat fusing the resultant mixtures, such as described in U.S. Pat. Nos. 4,560,766 and 4,654,424. Similarly, the halogenated hydantoins can be utilized in combination with 1,3-bromochloro-5-methyl-5-propylhydantoin as a binder as described in published PCT Application WO 97/43264.
While there are no hard and fast rules governing differentiation with respect to size among granules, tablets, briquettes, and pucks, typically granules are regarded as being particles ranging in size from about 80 to about 3 U.S. standard mesh size. Tablets typically fall in the range of from about 0.5 to about 1.0 inch in diameter and about 0.5 to about 1.0 inch in thickness. Briquettes will normally range in size from about 0.5 to about 4.0 inches in length, from about 0.5 to about 4.0 inches in width, and from about 0.5 to about 2.5 inches in thickness. Pucks are normally disc-shaped objects having a diameter up to about 3.0 inches and a thickness in the range of about 0.5 to about 1.0 inch. It will be understood and appreciated however, that these dimensions are not intended to unduly limit the scope of this invention.
If desired, the halogenated hydafitoins can be formulated with suitable excipients such as binders, lubricants, disintegrants, and mold release agents. Other optional ingredients which may be used in the formulation of compacted products from these halogenated hydantoins include fragrances, stabilizers, corrosion inhibitors, dyes, other biocidal agents, surfactants, effervescents, diluents, builders, chelating agents, and the like. Such ancillary materials should of course be compatible with the halogenated hydantoin and not interfere in any material way with the performance characteristics of the halogenated hydantoin. The amount(s) of such ancillary materials used should of course be sufficient to serve the purpose for which it is, or they are, being used. At the same time, the amount used should not materially detract from the physical, mechanical, or performance properties of the formulated product.
As indicated above, the halogenated hydantoins can be compacted with or without use of a binder. In the practice of this invention it is preferred to conduct the compaction in the absence of a binder. Commonly-owned co-pending application Ser. No. 09/487,816, filed Jan. 18, 2000, relates in part to the compaction of the halogenated hydantoins using novel binders described therein.
The following Examples are presented to illustrate the practice of, and advantages made possible by, this invention. These Examples are not intended to limit, and should not be construed as limiting, the scope of this invention to the particular operations or conditions described therein.
All particle size determinations referred to in the following Examples were determined by use of a Coulter(copyright) LS Particle Size Analyzer. The analyzer was equipped with an LS 230 small volume module and a Fraunhofer PIDS (Polarization Intensity Differential Scattering) detector switched to the xe2x80x9cOnxe2x80x9d position. The determinations were performed at room temperature with a run time of approximately 1 minute per sample. Prior to conducting the particle size determination, and whenever the sample appeared to contain particles adhering to each other, the sample was subjected for 15xc2x11 seconds to sonication using a Sonicor Model SC-100T apparatus to ensure that the particle size measurements were on individual particles of the product, rather than temporarily agglomerated particles.